The problems in sleep disorder medicine caused by the cost, access and variety of sleep laboratory testing have led to increasing use of home testing with oximeters for screening and triage of patients with suspected sleep apnea. Current oximeters are designed for hospital use and not for sleep medicine. They are complex and difficult to use for unattended recordings. They process the signal to reduce movement artifacts thereby reducing accuracy for apneas. This project will develop a new fully ambulatory oximeter (OxiTrac) designed for unattended recording in the home for two or more consecutive nights. OxiTrac will be worn like a wristwatch with a short cable connecting to a finger probe. Activity monitoring will be fully integrated into the unit for direct artifact detection reducing errors introduced by the amount of signal processing in current oximeters. Heart rate, SaO2, and activity will be stored in the unit and later downloaded to a computer for display and automatic analyses. In phase I the OxiTrac prototype was developed and successfully used, establishing feasibility. In phase II the unit will be improved, automatic artifact detection and data analyses developed and clinical evaluation completed. PROPOSED COMMERCIAL APPLICATIONS: The prevalence of the sleep apnea syndrome (SAS) is estimated at between 4 to 8% of the population. The high consequences of this disease and the cost of polysomnography make simplified recording techniques for screening and diagnosing imperative. Pulse oximetry has become a primary measure of choice in the evaluation of SAS and other sleep-related breathing disorders. The OxiTrac unit if established as a standard, would be suitable for use by the specialist, family doctor, nurse and most clinical staff and sold to virtually all sleep disorder centers, researchers, physicians, home testing agencies and similar clinical environments.